Fix CI by removing gen_pyi from mypy-stirct.ini (pytorch#48961)

Summary:
Fixes #{issue number}

Pull Request resolved: pytorch#48961

Reviewed By: janeyx99

Differential Revision: D25383152

Pulled By: malfet

fbshipit-source-id: ce0226398522342256d0d701edc13955d1095a0d

mypy-strict.ini

@@ -35,7 +35,6 @@ files = tools/codegen/gen.py,
     tools/autograd/gen_trace_type.py,
     tools/autograd/gen_variable_factories.py,
     tools/autograd/load_derivatives.py,
-    tools/pyi/gen_pyi.py,
     torch/utils/benchmark/utils/common.py,
     torch/utils/benchmark/utils/timer.py,
     torch/utils/benchmark/utils/valgrind_wrapper/*.py,